From leafy greens full of gut-friendly fiber to crunchy carrots packed with immune-boosting beta carotene, vegetables are an essential part of our diets and key sources of the nutrients we need on a daily basis.

What's more? Veggies are also naturally low in calories, fat and cholesterol, according to the United States Department of Agriculture (USDA), making them a smart choice when it comes to dropping to or maintaining a healthy weight.

The 2015-2020 Dietary Guidelines for Americans, which are compiled by the USDA and the U.S. Department of Health and Human Services, recommend that adults who consume an average number of calories (1,800 to 2,400 daily) get 2 1/2 to 3 cups of vegetables every day. However, since some are more nutrient-dense than others, what exactly counts as a cup can vary from veggie to veggie.

Confusing, right? But it doesn't have to be. Below, we break it down for you by comparing servings sizes of 10 popular veggies to common everyday objects, along with calorie counts (from the USDA's Food Composition Database) and other key nutrition info. So whatever your dietary goal, you can easily calculate just how much of the good stuff you're getting.

Asparagus

A 1-cup serving of asparagus is five medium stalks, which together are about the size of a dollar bill.
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Serving: 5 medium stalks

About the size of... a $1 bill

Calories: 16

Asparagus is a great source of vitamin K, which helps regulate blood flow and blood pressure, according to the NIH. A few stalks also serve up a good amount of potassium, a mineral that's especially important for active people because it plays a key role in hydration and supports good nerve and muscle function, per MedlinePlus.

Broccoli

A 1-cup serving of broccoli is one medium stalk, which is about the size of a hairbrush.
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Brussels Sprouts

Five Brussels sprouts equal a 1-cup serving, and each is about the size of a large egg.
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Serving: 5 large Brussels sprouts

About the size of... 5 large eggs

Calories: 38

A serving of these cabbage-like sprouts packs in more than your daily minimum requirement of vitamins C and K, per the USDA. You may know that vitamin C helps bolster your immune system and also acts as an antioxidant that protects your cells from harmful molecules called free radicals. But here's another perk to this powerful little nutrient: It helps keep the connective tissues throughout your body strong and healthy.

Carrot

A 1-cup serving of carrots is equal to one 7-inch carrot, which is about the size of a dinner fork.
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Serving: One 7-inch carrot

About the size of... a dinner fork

Calories: 30

Carrots are rich in beta carotene, which helps promote good vision and immune system development, according to Penn State Hershey Medical Center. A serving of carrots (which is equal to 12 baby carrots, in case you were wondering) is also high in biotin, a nutrient best known for supporting healthy hair, according to the NIH.

Cauliflower

A 1-cup serving of cauliflower is about the size of a baseball.
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Serving: 1/2 a small head

About the size of... a baseball

Calories: 27

Cauliflower has become a staple lower-carb alternative for foods like rice or even pizza crust, with only about 5 grams of carbohydrates per serving, according to the USDA. The cruciferous veggie is also a good source of choline, a vital nutrient that helps regulate mood, memory and muscle control, according to the NIH.

Celery

Two medium stalks of celery equal a 1-cup serving, and each stalk is about the size of a barber's comb.
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Serving: 2 medium stalks

About the size of... 2 barber's combs

Calories: 12

Celery is nearly 95 percent water and is commonly referred to as a "negative calorie food" due to its low calorie count and high fiber content, according to the Mayo Clinic. While there's no evidence to support this claim, celery is a healthy, fibrous veggie to include in your diet.

Leafy Greens

A serving of leafy greens is 2 cups, which are each about the size of a shower loofah.
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Serving: 2 cups, loosely packed

About the size of... two large shower loofahs

Calories: Dark leafy greens are very low in calories:

Arugula: 5

Kale: 7

Romaine: 8

Spinach: 7

A serving of romaine lettuce provides more than half of your daily recommended intake of vitamin A, per the USDA. Vitamin A supports healthy vision as well as the reproductive system, according to the Mayo Clinic.

Two heaping, double handfuls of spinach also provide vitamin A as well as folate, a B vitamin your body needs to carry out daily functions — from keeping your muscles strong to supporting hair and skin health, according to the National Institutes of Health (NIH).

Peppery arugula is high in vitamin K, which keeps your blood flow healthy, according to the Mayo Clinic.

Often touted as a superfood, nutrient-dense kale boasts high levels of vitamins C and A, according to the USDA, along with a little bit of plant protein.

All leafy greens are known for their high fiber content, which helps keep your digestion regular. And bonus: A diet full of fiber may help reduce your risk of developing heart disease, type 2 diabetes and some types of cancer, according to a November 2015 position paper published in the Journal of the Academy of Nutrition and Dietetics.